claire Stragier - Academia.edu (original) (raw)
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Papers by claire Stragier
bioRxiv (Cold Spring Harbor Laboratory), Mar 27, 2022
1. The development of methods for individual identification in wild species and the refinement of... more 1. The development of methods for individual identification in wild species and the refinement of Capture-Mark-Recapture (CMR) models during the past decades has greatly improved the assessment of population demographic rates to answer ecological and conservation questions. In particular, multistate models, with their flexibility for the analysis of complex study systems, have become popular in the ecological community. However, despite the extensive use of these models, little attention has been paid to the effect of common violations of the CMR model assumptions, such as mark loss and the often-associated recycling of remarked individuals. 2. To explore this knowledge gap we used a wide range of simulation scenarios reflecting frequently encountered real case studies inspired from the survival rates of 700 vertebrates' species. We estimated the effects of mark loss and recycled individuals on parameter estimates using a multistate Cormack-Jolly-Seber (MSCJS) framework. We explored parameter bias through simulations of a metapopulation system with different capture and survival rates. We also illustrated how mark loss can be easily estimated and accounted for using an empirical long-term (10 years) CMR dataset of bats, individually identified using both PIT tag technology as marks that can be lost, and multilocus genotypes as 'permanent marks'. 3. The results from our simulated scenarios demonstrated that the occurrence of bias and the parameters concerned were highly dependent on the study system, and no general rules on parameter behaviour can be established a priori. The model structure and the interdependency among parameters make it challenging to predict how bias could affect estimates. 4. Our results highlight the need to assess the effect of mark loss when using MSCJS models. Ignoring such violations of model assumptions can have important implications for ecological inferences and conservation policies. In general, the use of permanent marks (e.g. genotype), should always be preferred when modelling of population dynamics and if not possible, combining two types of temporary marks (e.g. PIT tags, bands) should be considered. .
Population genetic approaches may be used to investigate dispersal patterns of species living in ... more Population genetic approaches may be used to investigate dispersal patterns of species living in highly urbanized environment in order to improve management strategies for biodiversity conservation or pest control. However, in such environment, population genetic structure may reflect both current features of the cityscape and urbanization history. This can be especially relevant when focusing on exotic commensal rodents that have been introduced in numerous primary colonial European settlements. Accounting for spatial and temporal cityscape heterogeneity to determine how past and recent demographic events may interplay to shape current population genetic structure of synanthropic rodents may provide useful insights to manage their populations. In this study, we addressed these issues by focusing on the house mouse,Mus musculus domesticus, in Dakar, Senegal, where the species may have been introduced as soon as Europeans settled in the middle of the nineteenth century. We examined g...
Infection, Genetics and Evolution, Mar 1, 2020
Toxoplasma gondii is a ubiquitous highly prevalent zoonotic protozoan. Cats are the definitive ho... more Toxoplasma gondii is a ubiquitous highly prevalent zoonotic protozoan. Cats are the definitive hosts, while all other warm-blooded animals are intermediate hosts for this parasite. Commensal rodents, being the main prey of cats, are probably the major reservoir for T. gondii in the domestic environment. Rodents can acquire infection after ingestion of oocysts that have sporulated in the environment. However, experimental evidence shows that vertical transmission can be sufficient for the perpetuation of transmission between generations of mice. In natural settings, the relative epidemiological importance of vertical transmission over oral transmission is a matter of debate and raises the question of the possibility of a T. gondii cycle in the absence of cats. In the present study, we took advantage of an extensive survey of commensal rodents in Dakar, Senegal, where the house mouse is the predominant putative reservoir of T. gondii. Mice genotypes and spatial location through GPS referencing of all trapping localizations were investigated in relation to T. gondii infection in eight sites of the city of Dakar and on Goree Island. In each sampling site, the occurrence of over-prevalence zones of T. gondii infection was investigated through Kulldorf's statistic using SaTScan software. Genetic structure and relatedness between mice were investigated within each over-prevalence zone, in order to find clues of transmission between related mice. Within each of the four over-prevalence zones identified across nine sites, infected mice belonged to more than one genetic group. No association between the degree of relatedness and the occurrence of T. gondii infection could be detected. These findings suggest an environmental source of infection for mice associated with localized putative foci of environmental contamination and support an oral route of infection for mice from Dakar rather than a cycle based on vertical transmission. However, further investigations based on a denser sampling in different epidemiological contexts are recommended.
Population genetics of human commensal species within cities may reflect current features of the ... more Population genetics of human commensal species within cities may reflect current features of the cityscape, including socio-economic aspects, as well as urbanization history. Understanding genetic structure of archetypal commensals such as rodent pests may provide useful insights to manage their populations. In this study, we addressed these issues by focusing on the house mouse Mus musculus domesticus in Dakar, Senegal. The house mouse is a major synanthropic rodent who may have been introduced as soon as Dakar was settled by Europeans at the middle of the nineteenth century. We examine genetic variation at one mitochondrial locus and 15 nuclear microsatellite markers, in mice from 14 sampling sites representing different stages of urbanization history and different socio-economic environments in Dakar. We further investigate the influence of the historical and current features of the cityscape of Dakar on genetic structure of the house mouse, using a landscape genetic approach. Ge...
Infection, Genetics and Evolution
Toxoplasma gondii is an ubiquitous highly prevalent zoonotic protozoan. Cats are the definitive h... more Toxoplasma gondii is an ubiquitous highly prevalent zoonotic protozoan. Cats are the definitive hosts, while all other warm-blooded animals are intermediate hosts for this parasite. Commensal rodents, being the main preys of cats, are probably the major reservoir for T. gondii. Rodents often develop dormant tissue cysts after ingestion of oocysts shed in the environment by cats in the form of contaminated feces. Experimental evidence that vertical transmission can be sufficient to the perpetuation of transmission between generations of mice has also been found. In natural settings, the relative epidemiological importance of vertical transmission over oral transmission is a matter of debate and raises the question of the possibility of a T. gondii cycle in the absence of cats. In the present study, we took advantage of an extensive survey of commensal rodents in Dakar, Senegal, where the house mouse Mus musculus domesticus is the predominant putative reservoir of T. gondii. Host geno...
International Journal for Parasitology
bioRxiv (Cold Spring Harbor Laboratory), Mar 27, 2022
1. The development of methods for individual identification in wild species and the refinement of... more 1. The development of methods for individual identification in wild species and the refinement of Capture-Mark-Recapture (CMR) models during the past decades has greatly improved the assessment of population demographic rates to answer ecological and conservation questions. In particular, multistate models, with their flexibility for the analysis of complex study systems, have become popular in the ecological community. However, despite the extensive use of these models, little attention has been paid to the effect of common violations of the CMR model assumptions, such as mark loss and the often-associated recycling of remarked individuals. 2. To explore this knowledge gap we used a wide range of simulation scenarios reflecting frequently encountered real case studies inspired from the survival rates of 700 vertebrates' species. We estimated the effects of mark loss and recycled individuals on parameter estimates using a multistate Cormack-Jolly-Seber (MSCJS) framework. We explored parameter bias through simulations of a metapopulation system with different capture and survival rates. We also illustrated how mark loss can be easily estimated and accounted for using an empirical long-term (10 years) CMR dataset of bats, individually identified using both PIT tag technology as marks that can be lost, and multilocus genotypes as 'permanent marks'. 3. The results from our simulated scenarios demonstrated that the occurrence of bias and the parameters concerned were highly dependent on the study system, and no general rules on parameter behaviour can be established a priori. The model structure and the interdependency among parameters make it challenging to predict how bias could affect estimates. 4. Our results highlight the need to assess the effect of mark loss when using MSCJS models. Ignoring such violations of model assumptions can have important implications for ecological inferences and conservation policies. In general, the use of permanent marks (e.g. genotype), should always be preferred when modelling of population dynamics and if not possible, combining two types of temporary marks (e.g. PIT tags, bands) should be considered. .
Population genetic approaches may be used to investigate dispersal patterns of species living in ... more Population genetic approaches may be used to investigate dispersal patterns of species living in highly urbanized environment in order to improve management strategies for biodiversity conservation or pest control. However, in such environment, population genetic structure may reflect both current features of the cityscape and urbanization history. This can be especially relevant when focusing on exotic commensal rodents that have been introduced in numerous primary colonial European settlements. Accounting for spatial and temporal cityscape heterogeneity to determine how past and recent demographic events may interplay to shape current population genetic structure of synanthropic rodents may provide useful insights to manage their populations. In this study, we addressed these issues by focusing on the house mouse,Mus musculus domesticus, in Dakar, Senegal, where the species may have been introduced as soon as Europeans settled in the middle of the nineteenth century. We examined g...
Infection, Genetics and Evolution, Mar 1, 2020
Toxoplasma gondii is a ubiquitous highly prevalent zoonotic protozoan. Cats are the definitive ho... more Toxoplasma gondii is a ubiquitous highly prevalent zoonotic protozoan. Cats are the definitive hosts, while all other warm-blooded animals are intermediate hosts for this parasite. Commensal rodents, being the main prey of cats, are probably the major reservoir for T. gondii in the domestic environment. Rodents can acquire infection after ingestion of oocysts that have sporulated in the environment. However, experimental evidence shows that vertical transmission can be sufficient for the perpetuation of transmission between generations of mice. In natural settings, the relative epidemiological importance of vertical transmission over oral transmission is a matter of debate and raises the question of the possibility of a T. gondii cycle in the absence of cats. In the present study, we took advantage of an extensive survey of commensal rodents in Dakar, Senegal, where the house mouse is the predominant putative reservoir of T. gondii. Mice genotypes and spatial location through GPS referencing of all trapping localizations were investigated in relation to T. gondii infection in eight sites of the city of Dakar and on Goree Island. In each sampling site, the occurrence of over-prevalence zones of T. gondii infection was investigated through Kulldorf's statistic using SaTScan software. Genetic structure and relatedness between mice were investigated within each over-prevalence zone, in order to find clues of transmission between related mice. Within each of the four over-prevalence zones identified across nine sites, infected mice belonged to more than one genetic group. No association between the degree of relatedness and the occurrence of T. gondii infection could be detected. These findings suggest an environmental source of infection for mice associated with localized putative foci of environmental contamination and support an oral route of infection for mice from Dakar rather than a cycle based on vertical transmission. However, further investigations based on a denser sampling in different epidemiological contexts are recommended.
Population genetics of human commensal species within cities may reflect current features of the ... more Population genetics of human commensal species within cities may reflect current features of the cityscape, including socio-economic aspects, as well as urbanization history. Understanding genetic structure of archetypal commensals such as rodent pests may provide useful insights to manage their populations. In this study, we addressed these issues by focusing on the house mouse Mus musculus domesticus in Dakar, Senegal. The house mouse is a major synanthropic rodent who may have been introduced as soon as Dakar was settled by Europeans at the middle of the nineteenth century. We examine genetic variation at one mitochondrial locus and 15 nuclear microsatellite markers, in mice from 14 sampling sites representing different stages of urbanization history and different socio-economic environments in Dakar. We further investigate the influence of the historical and current features of the cityscape of Dakar on genetic structure of the house mouse, using a landscape genetic approach. Ge...
Infection, Genetics and Evolution
Toxoplasma gondii is an ubiquitous highly prevalent zoonotic protozoan. Cats are the definitive h... more Toxoplasma gondii is an ubiquitous highly prevalent zoonotic protozoan. Cats are the definitive hosts, while all other warm-blooded animals are intermediate hosts for this parasite. Commensal rodents, being the main preys of cats, are probably the major reservoir for T. gondii. Rodents often develop dormant tissue cysts after ingestion of oocysts shed in the environment by cats in the form of contaminated feces. Experimental evidence that vertical transmission can be sufficient to the perpetuation of transmission between generations of mice has also been found. In natural settings, the relative epidemiological importance of vertical transmission over oral transmission is a matter of debate and raises the question of the possibility of a T. gondii cycle in the absence of cats. In the present study, we took advantage of an extensive survey of commensal rodents in Dakar, Senegal, where the house mouse Mus musculus domesticus is the predominant putative reservoir of T. gondii. Host geno...
International Journal for Parasitology